Analysis and measurement of temporal tissue variations

Abstract

A method for real-time analysis and measurement of temporal tissue variations and ultrasonic signals which provides quality improvement of tissue images and qualitative and quantitative characterization of the size/shape of the imaged objects is described. A given number of image frames are stored and made available for digital data analysis. For each spatial coordinate, the temporal signal evolution or a derived temporal signal evolution is extracted. These evolutions are analyzed digitally and the resulting image can be displayed on a display unit as an improved 2D tissue image and/or an indicator image for a particular tissue or fluid category in the imaged scene. The resulting image can be further processed with a spatial filter investigating a plurality of neighboring scan lines and a plurality of neighboring ranges at each image coordinate and finally thresholded in order to obtain a binary indicator of the imaged objects that are detected in the combined time and space characterization.

We claim: 
     
       1. A method for real-time analysis and measurement of variations in ultrasonic signals comprising the steps of: acquiring and storing a predetermined number ultrasonic image frames;   updating the stored number of image frames with deletion of the oldest frame and inclusion of a new image frame;   making the stored number of image frames available for digital data analysis;   digitally analyzing the temporal evolution at each spatial coordinate in the stored ultrasonic image frames;   storing the result of the temporal analysis as a non-binary indicator image; and   displaying said non-binary indicator image on a display unit.   
     
     
       2. The method according to claim 1, further comprising the steps of: processing of the non-binary indicator image with a spatially varying threshold level to produce a binary indicator image;   extracting a plurality of connected components from the binary indicator image;   extracting digital representations of the borders of the said connected components and making them available for real-time analysis with digital processing; and   in real-time displaying the area and other derived attributes associated with a plurality of the said connected components simultaneously.   
     
     
       3. The method according to claim 2, further comprising the step of digital integration of a sequence of said connected components extracted in a 3-dimensional ultrasound acquisition for reconstruction of a 3-dimensional geometry. 
     
     
       4. The method according to claim 2, further comprising the step of digital integration of said connected components from a given number of cineloops in a triggered 3-dimensional ultrasound acquisition for reconstruction of time dependent 3-dimensional geometry. 
     
     
       5. The method according to claim 2, further comprising the step of digital integration of said connected components from a real-time 3-dimensional ultrasound acquisition providing real-time, time dependent 3-dimensional geometry description. 
     
     
       6. The method according to claim 1, further comprising the steps of: storing the said ultrasonic image frames in a fixed sized first in first out queue of images and maintaining the recording order between the image frames;   quantizing the temporal signals with a given number of bits distributed among the image frames; and   using the said bit representation as a lookup address in a memory bank holding a precomputed representation of the temporal filter.   
     
     
       7. The method according to claim 6, further comprising the step of selecting a frame in the sequence of image frames and redirecting the flow of image frames such that the said non-binary indicator image replaces the selected image frame in the next time step when a new image frame has been acquired in order to achieve recursive filtering in a portion of the said sequence of image frames. 
     
     
       8. The method according to claim 6, further comprising the step of quantizing the values obtained in a sequence of image frames at a given spatial coordinate relative to a value associated with a selected image frame in the said sequence of image frames and then mixing the said value associated with the selected image frame with the filter result given by the value of the non-binary indicator image at the same spatial coordinate in order to reduce the number of bits in the said quantized bit representation. 
     
     
       9. The method according to claim 1, further comprising the steps of computing the said non-binary indicator image obtained by said temporal evolution analysis as an improved version of the 2D tissue B-scan image and   displaying it on a display unit in real-time.   
     
     
       10. The method according to claim 1, further comprising the step of applying a filter that locally preserves monotonic segments in the said temporal evolution analysis. 
     
     
       11. The method according to claim 10, further comprising the step of using an approximation of the temporal signals with a plurality of locally monotonic signals as a basis for the said analysis of temporal evolutions. 
     
     
       12. The method according to claim 1, further comprising the steps of computing the said non-binary indicator image obtained by the said temporal analysis as an indicator for a specific material, and   displaying it on a display unit in real-time.   
     
     
       13. The method according to claim 12, further comprising the step of using a measure of the temporal variance as a basis for the said analysis of temporal evolutions. 
     
     
       14. The method according to claim 12, further comprising the steps of spatially interpolating a number of scan lines between each measured scan line in the 2D ultrasonic images,   offsetting the position of the measured scan lines in a cyclic manner between each 2D image acquisition such that all scan lines are measured exactly once after a complete cycle, and   applying this sequence of images to the said temporal analysis.   
     
     
       15. The method according to claim 1, further comprising the step of processing of the said non-binary indicator image with a spatial neighborhood filter investigating a plurality of neighboring scan lines and a plurality of neighboring ranges before the said temporal indicator image is thresholded. 
     
     
       16. The method according to claim 15, further comprising the steps of computing the said filter by first thresholding the image, accumulating the number of image elements above the threshold level inside the said spatial neighborhood and   thresholding this number with a value depending on the size of the said spatial neighborhood.   
     
     
       17. The method according to claim 16, further comprising the step of regulating the size of the said spatial neighborhood such that the detection resolution can be regulated to match the quality of the underlying ultrasonic images. 
     
     
       18. A method for synthesizing at least one 3-dimensional geometry in 3-dimensional ultrasound imaging based on the results of a method for real-time analysis and measurement of temporal and/or spatial tissue variations in ultrasonic signals during investigation of living biological structures for quantitative and qualitative characterization of size/shape of the imaged objects including cavities, vessels, tissue categories or various blood perfusion levels in a given tissue category comprising the steps of: producing a binary indicator image based on the information content in a single 2D ultrasonic image frame or a sequence of 2D ultrasonic image frames in real-time,   extracting a plurality of connected components from the said binary indicator image, and   digitally reconstructing 3-dimensional geometries by integration of a sequence of said connected components extracted during a 3-dimensional ultrasound acquisition for reconstruction of a 3-dimensional geometry.   
     
     
       19. A method for synthesizing at least one 3-dimensional geometry in 3-dimensional ultrasound imaging based on the results of a method for real-time analysis and measurement of temporal and/or spatial tissue variations in ultrasonic signals during investigation of living biological structures for quantitative and qualitative characterization of size/shape of the imaged objects including cavities, vessels, tissue categories or various blood perfusion levels in a given tissue category comprising the steps of: producing a binary indicator image in real-time based on the information content in a single 2D ultrasonic image frame or a sequence of 2D ultrasonic image frames,   extracting a plurality of connected components from the said binary indicator image, and   digitally reconstructing 3-dimensional geometries by integration of a sequence of said connected components extracted during a triggered 3-dimensional ultrasound acquisition for reconstruction of time dependent 3-dimensional geometry.   
     
     
       20. A method for synthesizing at least one 3-dimensional geometry in 3-dimensional ultrasound imaging based on the results of a method for real-time analysis and measurement of temporal and/or spatial tissue variations in ultrasonic signals during investigation of living biological structures for quantitative and qualitative characterization of size/shape of the imaged objects including cavities, vessels, tissue categories or various blood perfusion levels in a given tissue category comprising the steps of: producing a binary indicator image in real-time based on the information content in a single 2D ultrasonic image frame or a sequence of 2D ultrasonic image frames,   extracting a plurality of connected components from the said binary indicator image, and   digitally reconstructing 3-dimensional geometries by integration of a sequence of said connected components extracted during a real-time 3-dimensional ultrasound acquisition providing real-time, time dependent 3-dimensional geometry description.